Sorry for the slow response on your post, I hope the rapid HR has passed.
You didn't say how fast it is, so it is hard to give any advice/reaction.
The guidance I'd follow myself is:
if under 100 bpm at rest, I'l wait a day or two to see what happens
if over 130 I'd call my primary care doctor
if over 200 I'd go to the emergency room
Taking the aspirin is a good idea, but one is enough for whatever benefit it may provide. I recommed taking aspirin with food.